Staphylococcus facecalis is the old term given to this strain of
bacteria. It is now known as Enterococcus faecalis, with a G+ Gram
reaction. It is possible to detect this bacteria using an SF plate
(glucose fermentation) which uses glucose as a substrate. The purple
color is due to the Bromcresol Purple indicator. E. faecalis can
withstand Sodium Azide (inhibits cytochrome oxidase/selects for
fermenters) and if is tested positive, will turn the purple color to
yellow(due to the lowered pH). I hope this information helps.
Sincerely,
Shayne Woodward
University of Maine
Biology Student